Systems allow passengers (also referred to as customers) to book trips having arrival and departure times that are pre-determined by a transportation service provider. Systems allow passengers to book trips having pre-determined origin and destination locations. Systems may book passengers into vehicles (e.g., buses, airplanes) having static capacities (e.g., a fixed number of seats available), and/or static stops and routes. For example, carpooling may have a fixed start and stop locations (e.g. to and from work) along with fixed travel times (e.g. in the morning and evening). The driver in a carpooling scenario may only pass by a given location at a fixed travel time (e.g. morning or evening). It may be desirable to have dynamic or virtual start and stop locations and various travel time options. The start and stop locations may also be referred to as pick up or drop off locations. There may be multiple vehicles for transporting multiple passengers, e.g., to provide numerous ride-shared trip options. It is desirable to provide a flexible, dynamic system that works with multiple vehicles and passengers.